According to assistant mammal curator Karen Vacco, Moka's increased appetite could be one of the signs. "Her appetite is increasing a little bit, and we are seeing a little bit of changes in her body," she said.

Moka, a western lowland gorilla, had her first baby last January (SEE PHOTOS) and was immediately a caring mother. But the mortality rate for first-time gorilla mothers is high 40 percent. The baby died four months later.

"It was tough. You know, we are really hopeful. We did have a positive pregnancy test, but with gorillas, it is not the same as with people," Vacco said, even though they use a human pregnancy test.

"It is a regular human, it's an EPT test, same as people. A plus or minus." When asked if the zoo got one at the drug store, Vacco said, " Pretty much."

And as with the first pregnancy, Mrithi, a hulking, imposing silverback, is the father. "He was our first gorilla ever born here. Full circle," Vacco said.

Zakula, the wild-caught mother of Mrithi now in her 40s, is why Mrithi's genes are so valuable to the highly endangered species, and why Moka and Mrithi are a match made in conservation heaven.

But keeper Roseann Giambro said it wasn't easy. "She totally ignored him at first. Now she's got him wrapped around her little finger, to put it in human terms," Giambro said.

And in almost human terms, Moka has learned from her first pregnancy and from her loss. "Her confidence level over the past year has grown considerably, and we are very optimistic that everything will be fine this time," said Vacco.

Gestation is eight months, but the staff is not sure when conception actually happened. When Moka was pregnant last year, she began to show early, and they fully expect her to do that this time.